The need for precision components in the area of optical fiber termination and connection assemblies is well known In connecting an optical fiber to a second fiber or another optical component, it is essential to provide a close tolerance alignment between the two components. In the special case of connecting two optical fibers, various fundamental factors affect the quality and reliability of the connection. These factors include quality of the end face of the fibers which are to be connected, the alignment of two fiber cores and the relative proximity of the end faces of the fibers which are connected.
Various techniques exist for preparing the end face of an optical fiber. These techniques include either scoring and breaking the fiber or grinding and polishing the fiber down to a flat end face. Each of these techniques attempts to provide a fiber end face which is substantially perpendicular to the axis of the fiber and is relatively free from dirt and debris, which would reduce the optical transmissive capabilities of the end face. Several tools and fixtures are available to prepare a fiber end face.
The efficiency of the connection is also affected by the accuracy with which the fibers are aligned. Greater optical efficiency is achieved when the fiber end faces are brought into close proximity. More importantly, however, is the accuracy of the core alignment, that is the accuracy with which the central axis of the fiber cores are aligned. Numerous fixtures are available which precisely support a pair of optical fibers in a position where the cores of the fibers are aligned. A typical fixture of this type includes an alignment member which accommodates prepared fiber ends from opposite sides thereof. The alignment member has a precision central bore therethrough which accommodates both of the fiber ends. The fibers may be then brought into abutting engagement to provide precise alignment. Alignment members of this type may take the form of a plurality of balls or rods which support the optical fiber in the intersticial space formed therebetween.
The art has also seen the use of additional or secondary alignment surfaces which aid in aligning the fibers and also provide a suitable structure for ease of handling. Secondary alignment elements include optical fiber ferrules which have precision apertures therethrough which accommodate the ends of optical fibers. These fiber ferrules may then be brought into contact with one another within the primary alignment member to dispose the end faces of the fibers in close proximity. One benefit of using a secondary alignment element such as a fiber ferrule is that the fiber may be supported initially in the ferrule and then fiber end face preparation may take place. This provides for ease of handling and connection. Since once prepared, the bare fiber need not be handled directly,, the chances of damage are reduced. Thus, a fiber may be inserted into a fiber ferrule and then scored adjacent the egressing end thereof to provide a fiber end face thereat. This end face may then be further prepared by grinding and polishing to make it flush with the egressing end of the ferrule.
One problem which has arisen with the technique of breaking the fiber and polishing the end face is that when the fiber is scored in the ferrule, quite often the crack propragation of the fiber may be toward the egressing end of the ferrule. If the fiber was to crack or break within the ferrule, the end face of the fiber could not be polished down to a perpendicular end face. Thus the fiber would have to be reterminated in another fiber ferrule.
In addition, problems may arise where the material with which the fiber ferrule is formed is incompatible with the fiber itself. A plastic fiber ferrule formed of a material softer than the fiber may present a problem when an attempt is made to grind and polish the end face of the fiber flush with the ferrule itself. Damage could be done to the ferrule which may cause problems in terminating two ferrules together. Similarly, a fiber ferrule formed of a material harder than the glass fiber, such as ceramic, may cause further problems during grinding and polishing. The fiber itself may be ground and polished below the end face of the ceramic ferrule thereby causing a gap between two fibers upon mating. Gaps such as these reduce the optical efficiency of the connection.
It is therefore desirable to provide an improved optical fiber support element which will support a optical fiber and provide for fiber end face preparation which avoids disadvantages of past practices.